The detection of hydrocarbons while drilling is currently limited to the analysis of C1-C6 hydrocarbons entrained in the drilling mud. This is typically conducted by desorption of returned mud followed by a gas chromatographic analysis. The service is offered by many well logging companies. Conventional systems combine a rigorous sampling system coupled to a mass spectrometer, allowing precise fluid logging and analysis in real time.
Several service companies offer some form of downhole sensing for hydrocarbons. Most are based on resistivity measuring the difference between oil and water. Nuclear Magnetic Resonance (NMR) well logging is known in the prior art, and is used to detect and differentiate flowable oil from solid bitumens.
Several service companies offer spectrographic hydrocarbon detection systems. Typically, for such systems, a tool is lowered by wireline and uses a spectrometric sensor to determine if fluid flowing from a specific interval is liquid, gas, oil or water. The array of detectors include near IR, or visible light. These sensors are mostly designed to determine if the fluid flowing into a sample chamber is formation oil and represents a valid sample to bring to the surface for testing.